Opening pandora’s box: incidental findings among infants referred from neonatal screening for metabolic disorders.

Purpose: Newborn screening refers to series of tests conducted within the first hours or days of a newborn's life to prevent severe health complications, including death. The study aims to investigate and document other findings and diseases that are incidentally detected through physical examination or laboratory results in infants referred due to elevated phenylalanine levels or biotinidase deficiency as a result of newborn screening. Methods: 792 newborns were referred and evaluated due to their dried blood phenylalanine levels above 120 μmol/L or biotinidase enzyme activity below 65 U. A total of 737 patients were included in the study. The demographic characteristics, reasons for referral, plasma phenylalanine and blood biotinidase levels as well as incidental pathological examination and laboratory findings at the time of referral were recorded for these patients. Results : A total of 25 (3.4%) patients were diagnosed with incidental conditions during screening, 16 of them (66.6%) were initially referred for biotinidase deficiency. Four patients were diagnosed with classical galactosemia, one per with lipoprotein lipase (LPL) deficiency, cystinuria, CPT II deficiency, Duchenne muscular dystrophy. Four patients had congenital heart disease, two were diagnosed with Down Syndrome, two had surgical problems as Hirschsprung's disease and diaphragmatic hernia. Four others had infectious and respiratory diseases, and other four patients had hyperbilirubinemia, feeding problems, extensive hemangioma and microcephaly. Conclusion : A systematic evaluation should be conducted carefully to identify incidental diseases especially for early recognition of conditions detected through newborn screening programs.